New Catalytic Distillation Process for the Production of the Fuel Ether TAME Using Different Pressure Thermally Coupled Technology

New catalytic distillation process for the production of the fuel ether TAME using different pressure thermally coupled technology

Hong Li^{a, *}, Xin Gao^a, Xingang Li^{a, b}

^a School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China

^b National Engineering Research Center for Distillation Technology, Tianjin 300072, China

Abstract

The integration of reaction and separation in one single process unit shows several advantages compared to the separately performed processes. Process intensification and energy integration represent ways of economical efficiency, as well as environmental friendly operating conditions. In this paper, the process of catalytic distillation for tert-amyl methyl ether (TAME) synthesis from isoamylenes (2M1B and 2M2B) and methanol has been studied. A brief description of equilibrium stage model developed is given for simulation of the catalytic distillation process of the synthesis of tert-amyl methyl ether (TAME) from isoamylenes (2M1B and 2M2B) and methanol. The model predicted the reaction conversion and the energy consumption of process. Validation based on pilot plant experiments proved that the model accuracy is satisfactory. A new process technology was designed by means of different pressure thermally coupled technology for energy-saving.

The conventional RD column for producing TAME consist of rectifying section, reactive section and stripping section. The column is operated at an overpressure of 0.4MPa°«0.5 Mpa. Increasing column pressure causes increased reaction rates and a shift of chemical equilibrium duo to higher boiling point temperatures in the reactive distillation section. On the other hand, increasing column pressure reduces the realative volatility. In odrer to providing a good recovery of 2M2B and improving the TAME purity in bottom product, the stripping section have to increasing the energy consumption of reboiler in catalytic distillation column bottom. So increasing the pressure of the stripping section is unnecessary.

Based on the analysis above, different pressure thermally coupled technology could be applied to the catalytic distillation process for producing TAME. In this process technology, the RD column is divided to two columns with different pressure. This unit is a highly integrated configuration as it contains a reactive part placed in higher pressure column, products separation in the lower pressure column. The process scheme used in our design study is shown in Fig.1. The flow scheme consists of a pre-reactor followed by a higher pressure RD column and a lower pressure stripping column. The top stream from the higher pressure RD column is used as the teat energy for the reboiling of the lower pressure stripping column, therefore the thermally coupled process is realized.

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Fig.1 The scheme of catalytic distillation process applied to different pressure thermally coupled technology for prducing TAME

A comparsion of conventional catalytic distillation process for producing TAME and new catalytic distillation process applied to different pressure thermally coupled technology for prducing TAME shows that the energy consumption of new process could be reduced about 46.7%. The purity of TAME obtained as bottom product of lower pressure stripping column is high, and the excess of methanol can be recirculated to the pre-reactor allowing a good overall yield of the process. Finally, the equilibrium stage model is used to optimal effect parameters and design factors of the new process technology on conversion and energy consumption. The catalytic distillation process integrated by different pressure thermally coupled technology seems to be a very attractive and challenging process.

Keywords: cataytic distillation, TAME, different pressure thermally coupled, process intensification

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* Corresponing author

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